• Title, Summary, Keyword: capillary rheometer

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PvT measruement method of polymer using capillary rheometer (캐필러리 레오미터를 이용한 고분자의 PvT 측정 방법)

  • Kim, Sun-Kyoung;Park, Jae-Un
    • Journal of the Korea Society of Die & Mold Engineering
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    • v.14 no.3
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    • pp.31-36
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    • 2020
  • In injection molding processes, the property of molten resin should be characterized accurately. Among several properties, the PvT state is the most important one, since it affects the shrinkage, warpage, molded weight, and the part density. Thus, the PvT data is crucial to the simulation of the injection molding process. This work shows how such a measurement can be performed for a semi-crystalline and amorphous polymers. The PvT measurement has been conducted using a capillary rheometer using a suitable accessory that blocks the capillary. The results have shown that the PvT data can be obtained using such a rheometer and then the PvT coefficients of the Tait equation can be reached.

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Plasticity Evaluation of Porcelain Body Depend on Aging Period and Water Content Change Using Capillary Rheometer (Capillary Rheometer를 이용한 숙성시간 및 함수율 변화 도자소지의 가소성평가)

  • Kim, Geun-Hee;Pee, Jae-Hwan;Kim, Jin-Ho;Kim, Young-Hwan;Cho, Woo-Seok;Kim, Kyeong-Ja
    • Journal of the Korean Ceramic Society
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    • v.49 no.3
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    • pp.231-235
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    • 2012
  • Plasticity is the ability of clay to respond to pressure with a continuous and permanent change of shape in any direction without breaking apart, and hold that shape when released. In this work, the effect of water content and aging period on the plasticity of porcelain clay was evaluated using the capillary rheometer to measure the flow rate and the shear stress. The shear stress of porcelain clay was slightly increased with increasing the aging period, indicating that the plasticity of porcelain clay was influenced by an organic content. It was also observed that the water content in the porcelain clay had a great influence on the plasticity of porcelain clay. The shear stress with water content of 21 wt% was sharply increased with increasing shear rate, but the shear stresses with water contents of 24 and 27 wt% is gently incremented.

Rheological Properties of a Partially Vulcanized Filled EPDM (부분적으로 가황된 EPDM 배합의 유변학적 특성)

  • Kim, Sang-Koo;Lee, Suck-Hyun
    • Elastomers and Composites
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    • v.22 no.3
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    • pp.213-218
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    • 1987
  • In this study, the rheological properties of a partially valcanized black filled EPDM were investigated as a function of degree of crosslinks using capillary rheometer. In order to obtain the samples having various degree of crosslinks between 0 and 6 percent, the vulcanization kinetics was also studied by Monsanto rheometer. The results showed that the die swell ana the pressure drop at the capillary entrance and exit increase nearly linearly with the increase in degree of crosslinks. However, melt fracture occurred at a lower shear rate for the samples of higher degree of crosslinks. These results were discussed in terms of the melt elasticity produced at the entrance region of capillary by the partial vulcanization. It is also interesting to note that the fluctuation of die swell during the practical extrusion or calendering process in the factories can be caused by the partial vulcanization occurred during the process.

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Optimization of Composite MIM Feedstock Rheological Behaviour by Experimental Analysis

  • Chen, Chih-Cherng;Wu, Chi-Wen;Yen, Chih-Ming
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.495-496
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    • 2006
  • The kneading process and formulations of feedstock obviously affect the quality of MIM products. In the present work, the rheological behaviour of the composite MIM feedstock, metal matrix (Cu) with few additions of ceramic powders $(Al_2O_3)$, was measured by a self-designed/manufactured simple capillary rheometer. Experimental results show that the distribution between powders and binder is more uniformly when blending time increased. Though high powder loading will increase the feedstock viscosity, the fluidity reveals relatively stable through the load curves of extrusion. Besides, the temperature-dependence of viscosity of the feedstock approximately follows an Arrehnius equation. Basing on Taguchi's method, the kneading optimization conditions and the rheological model of the feedstock were established, respectively.

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Coalescence of Dispersed Phase for Immiscible Polymer Blends in Quiescent Flow Field (정상 흐름 영역에서 비상용성 고분자 블렌드계의 분산상의 Coalescence 거동에 관한 연구)

  • 김영호;최관영;김호겸;서창욱;최진환
    • Polymer(Korea)
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    • v.26 no.3
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    • pp.316-325
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    • 2002
  • The deformation and coalescence behaviors of immiscible LDPE/PS blends (86.5/13.5 vol%) prepared by internal mixer were studied using rheometer and scanning electron microscope. The fine droplets coagulated at initial stage of mixing, and deformed fiber at large strain. The critical capillary number was calculated according to the empirical equation of De Bruijn and it was 0.95, the local capillary number was 3.867. The polymer blends were annealed at $200^{\circ}C$ for various time to investigate morphological change of polymer blends. The maximum size of droplet after annealing at $200^{\circ}C$ was found at ${\gamma}$=1798, and there was destruction of the morphology at 15 minutes of annealing time. The viscosity of matrix was critical to determine a coalescence of droplet.

Rheological behavior of dilute bubble suspensions in polyol

  • Lim, Yun-Mee;Dongjin Seo;Youn, Jae-Ryoun
    • Korea-Australia Rheology Journal
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    • v.16 no.1
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    • pp.47-54
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    • 2004
  • Low Reynolds number, dilute, and surfactant-free bubble suspensions are prepared by mechanical mixing after introducing carbon dioxide bubbles into a Newtonian liquid, polyol. The apparent shear viscosity is measured with a wide-gap parallel plate rheometer by imposing a simple shear flow of capillary numbers(Ca) of the order of $10^{-2}$ ~ $10^{-1}$ and for various gas volume fractions ($\phi$). Effects of capillary numbers and gas volume fractions on the viscosity of polyol foam are investigated. At high capillary number, viscosity of the suspension increases as the gas volume fraction increases, while at low capillary number, the viscosity decreases as the gas volume fraction increases. An empirical constitutive equation that is similar to the Frankel and Acrivos equation is proposed by fitting experimental data. A numerical simulation for deformation of a single bubble suspended in a Newtonian fluid is conducted by using a newly developed two-dimensional numerical code using a finite volume method (FVM). Although the bubble is treated by a circular cylinder in the two dimensional analysis, numerical results are in good agreement with experimental results.

Development of Powder Injection Molding Process for a Piezoelectric PAN-PZT Ceramics

  • Han, Jun Sae;Park, Dong Yong;Lin, Dongguo;Chung, Kwang Hyun;Bollina, Ravi;Park, Seong Jin
    • Journal of Korean Powder Metallurgy Institute
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    • v.23 no.2
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    • pp.112-119
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    • 2016
  • A powder injection molding process is developed and optimized for piezoelectric PAN-PZT ceramics. Torque rheometer experiments are conducted to determine the optimal solids loading, and the rheological property of the feedstock is evaluated using a capillary rheometer. Appropriate debinding conditions are chosen using a thermal gravity analyzer, and the debound specimens are sintered using sintering conditions determined in a preliminary investigation. Piezoelectric performance measures, including the piezoelectric charge constant and dielectric constant, are measured to verify the developed process. The average values of the measured piezoelectric charge constant and dielectric constant are 455 pC/N and 1904, respectively. Powder injection molded piezoelectric ceramics produced by the optimized process show adequate piezoelectric performance compared to press-sintered piezoelectric ceramics.

Flow Behavior of Polystyrene and Poly(butyl methacrylate) Composite Particles Filled with Varying Concentrations of Carbon Black (다양한 농도의 카본블랙을 함유하는 폴리스티렌 및 폴리뷰틸메타크릴레이트 복합체 입자의 유동성)

  • Park, Moon-Soo
    • Elastomers and Composites
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    • v.44 no.3
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    • pp.336-342
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    • 2009
  • We measured shear viscosity of polystyrene (PS) and poly(butyl methacrylate) (PBMA) particles, with a capillary rheometer, prepared by suspension polymerization with 1.0 wt% hydrophobic silica as a stabilizer by varying the initiator concentration at $75^{\circ}C$. PS particles with weight average molecular weight of 66,500 g/mol displayed a Newtonian behaior at low shear rates at $190^{\circ}C$. With increasing molecular weight, PS particles showed shear thinning over the entire range of shear rates. For PBMA particles, steady shear measurement was carried out at $170^{\circ}C$. PBMA particles with weight average molecular weight of 156,700 g/mol showed a Newtonian behaior only at low shear rates. PBMA particles also showed shear thinning with an increase in molecular weight and its pattern similar to that of PS. When carbon black was incorporated into PS and PBMA polymers, steady shear measurement was conducted at $170^{\circ}C$. An increase in carbon black concentration in PS and PBMA composite particles exhibited a progressive increase in shear viscosity. The increase in shear viscosity, however, was less pronounced compared to an increase as a function of molecular weight. Preparing PS composites containing carbon black by internal mixing resulted in an increase in shear viscosity. Its increase, however, was found to be less than that shown in PS composite particles. We speculate that this is caused by an enhanced dispersion of carbon black particles with an internal mixer. Yield behavior was not observed in any of the samples we selected in this experiment.

Numerical simulation of a single bubble suspension in polyol resin

  • Dongjin Seo;Lim, Yun-Mee;Youn, Jae-Ryoun
    • Proceedings of the Korean Fiber Society Conference
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    • pp.47-48
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    • 2003
  • Dilute bubble suspensions are prepared by introducing carbon dioxide bubbles into polyol resin. The apparent shear viscosity is measured with a wide gap parallel plate rheometer. A numerical simulation for deformation of a single bubble suspended in a Newtonian fluid is conducted by using a finite volume method (FVM) where multigrid algorithms are incorporated. Transient and steady results of bubble deformation were obtained and were in good agreement with experimental results. At high capillary number, viscosity of the suspension increases as the volume fraction increases, while at low capillary number, the viscosity decreases as the volume fraction increases.

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